We are proposing the dedication of a demographically balanced population of 286 physically, behaviorally, and reproductively healthy rhesus monkeys to a derivation strategy designed to establish and maintain a financially independent SPF (retrovirus and HBV negative) rhesus production colony. Preliminary representative serological surveys indicate this population is retrovirus free (except for a low incidence of STLV-1/HTLV-1 in animals over seven (7) years of age). The HBV status is typical of most conventional colonies so the derivation strategy is oriented towards intensive screening and separation to establish a HBV negative breeding colony during the award period. The breeding plan and facilities has a 14 year track record to substantiate the success of the breeding program and the cost- effective delivery of high quality husbandry and care. The physical facilities and site characterisitcs insure a balance between an enriched and protected animal habitat. To complement the facilities, sufficient numbers of dedicated and experienced professional and technical personnel are available to assure programmatic success. We offer a professional staff with a combined 44 years of experience in primate care and management and a technical animal care cadre with over 29 years of combined experience. Through collaborative subcontracts, consultantships, and companion research proposals, we have built a programmatic consortium that satisfies all stated goals of disease and genetic monitoring: provides a breeding plan which maximizes animal well-being and safety, and produces a behaviorally normal, reproductively competent, and healthy SPF offspring. The breeding colony will serve as a core resource to support research efforts in: 1) developing behavioral strategies for improving the well-being of captive rhesus monkeys; 2) genetic typing and gene frequency determinations, essential to maintaining colony heterogeneity, and genetically managing populations through selective breeding for preferred health and behavioral traits, 3) developing more sensitive, accurate and standardized assays for identifying animals free of HBV infection; 4) evaluating the usefulness of embryo transfer for the production and introduction of new genetic material into SPF colonies.